Floating storage and offloading (FSO) vessels keep station using a system of mooring lines terminating at anchoring means, such as suction piles. The mooring lines typically include multiple segments, including at least one chain segment at the anchor and, one chain segment at the FSO, and a wire rope segment there between. The wire rope is made up of multiple strands of steel and is subject to corrosion in a subsea environment over time. For instance, a wire rope having a diameter of about 4 inches may have a design life of about 7-10 years after which the wire rope must be decommissioned or removed. The entire mooring line can be replaced; however, this is extremely costly since the field production has to be shutdown to allow welding on the FSO. In order to replace the wire rope segment of the mooring line, the conventional way is to send divers down to seafloor to disconnect the old wire rope from the adjacent chain segments and connect a new wire rope to the adjacent chain segments. The divers perform the necessary subsea cuts and connections while on the seabed in poor visibility, and manually perform all related physical tasks including lifting. These are dangerous because of the weight and tension on the steel components. If weather turns severe, the divers may be trapped in the subsea environment until conditions are calmer that the boat could resume diving support.
It would be desirable to have a safer method to extend the life of the mooring line by replacing the old wire rope segment which would not require divers to perform operations subsea.